/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.scripting.groovy;

import java.io.IOException;
import java.util.Map;

import groovy.lang.Binding;
import groovy.lang.GroovyRuntimeException;
import groovy.lang.GroovyShell;

import org.codehaus.groovy.control.CompilerConfiguration;
import org.codehaus.groovy.control.customizers.CompilationCustomizer;

import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.lang.Nullable;
import org.springframework.scripting.ScriptCompilationException;
import org.springframework.scripting.ScriptEvaluator;
import org.springframework.scripting.ScriptSource;
import org.springframework.scripting.support.ResourceScriptSource;

/**
 * Groovy-based implementation of Spring's {@link ScriptEvaluator} strategy interface.
 *
 * @author Juergen Hoeller
 * @see GroovyShell#evaluate(String, String)
 * @since 4.0
 */
public class GroovyScriptEvaluator implements ScriptEvaluator, BeanClassLoaderAware {

    @Nullable
    private ClassLoader classLoader;

    private CompilerConfiguration compilerConfiguration = new CompilerConfiguration();


    /**
     * Construct a new GroovyScriptEvaluator.
     */
    public GroovyScriptEvaluator() {
    }

    /**
     * Construct a new GroovyScriptEvaluator.
     *
     * @param classLoader the ClassLoader to use as a parent for the {@link GroovyShell}
     */
    public GroovyScriptEvaluator(@Nullable ClassLoader classLoader) {
        this.classLoader = classLoader;
    }

    /**
     * Return this evaluator's compiler configuration (never {@code null}).
     *
     * @see #setCompilerConfiguration
     * @since 4.3.3
     */
    public CompilerConfiguration getCompilerConfiguration() {
        return this.compilerConfiguration;
    }

    /**
     * Set a custom compiler configuration for this evaluator.
     *
     * @see #setCompilationCustomizers
     * @since 4.3.3
     */
    public void setCompilerConfiguration(@Nullable CompilerConfiguration compilerConfiguration) {
        this.compilerConfiguration =
                (compilerConfiguration != null ? compilerConfiguration : new CompilerConfiguration());
    }

    /**
     * Set one or more customizers to be applied to this evaluator's compiler configuration.
     * <p>Note that this modifies the shared compiler configuration held by this evaluator.
     *
     * @see #setCompilerConfiguration
     * @since 4.3.3
     */
    public void setCompilationCustomizers(CompilationCustomizer... compilationCustomizers) {
        this.compilerConfiguration.addCompilationCustomizers(compilationCustomizers);
    }

    @Override
    public void setBeanClassLoader(ClassLoader classLoader) {
        this.classLoader = classLoader;
    }


    @Override
    @Nullable
    public Object evaluate(ScriptSource script) {
        return evaluate(script, null);
    }

    @Override
    @Nullable
    public Object evaluate(ScriptSource script, @Nullable Map<String, Object> arguments) {
        GroovyShell groovyShell = new GroovyShell(
                this.classLoader, new Binding(arguments), this.compilerConfiguration);
        try {
            String filename = (script instanceof ResourceScriptSource ?
                               ((ResourceScriptSource) script).getResource().getFilename() : null);
            if (filename != null) {
                return groovyShell.evaluate(script.getScriptAsString(), filename);
            } else {
                return groovyShell.evaluate(script.getScriptAsString());
            }
        } catch (IOException ex) {
            throw new ScriptCompilationException(script, "Cannot access Groovy script", ex);
        } catch (GroovyRuntimeException ex) {
            throw new ScriptCompilationException(script, ex);
        }
    }

}
